Field of the Invention
The present invention relates to a manufacturing method of a honeycomb structure, and a grinding wheel. More particularly, it relates to a manufacturing method of a honeycomb structure in which end faces of a honeycomb formed body formed by extrusion are ground to finish the end face, and a grinding wheel for use in the manufacturing method.
Description of the Related Art
Heretofore, a honeycomb structure made of ceramics (hereinafter simply referred to as “the honeycomb structure”) has broadly been used in a use application such as a car exhaust gas purifying catalyst carrier, a diesel particular removing filter, or a heat reservoir for a burning device. The honeycomb structure is manufactured through a forming step of mixing and preparing a forming raw material (a kneaded material) and then extruding the material into a desirable honeycomb shape (e.g., a round pillar shape) through an extruder; a raw cutting step of rawly cutting an extruded honeycomb formed body into a predetermined length; a drying step of combining induction drying and hot air drying, and drying the honeycomb formed body; a finishing step of performing end face finishing of the dried honeycomb formed body; and a firing step of firing the honeycomb formed body at a high temperature.
In the raw cutting step, the longitudinal uncut honeycomb formed body extruded by the extruder is cut into the predetermined length by use of a cutting tool such as a fine metal wire. The honeycomb formed body immediately after extruded and before drying contains a lot of water, and is soft. Therefore, the honeycomb formed body can easily be cut by utilizing the metal wire or the like. However, when the honeycomb formed body comes in contact with the metal wire, the whole shape of the honeycomb formed body might be deformed, or a cut surface of the honeycomb formed body with the metal wire might be deformed (cells might mainly be deformed).
Therefore, after the drying step, the finishing step is carried out to perform end face finishing in which the end faces of the honeycomb formed body are processed, and cell deformation or the like caused by the above raw cutting step is removed.
In the case of a honeycomb structure having a large diameter (hereinafter referred to as “the large-size honeycomb structure”), in the above finishing step, there are performed a finish cutting step of passing both end portions of the honeycomb formed body subjected to the drying step through a space between a pair of cutters disposed away from each other to cut the end portions, and an end face grinding step of performing end face grinding of the end faces (cut surfaces) of the honeycomb formed body by use of a well-known cup type grinding wheel 100 (see FIG. 8) to remove chippings or feed marks generated in the end faces in the finish cutting step (e.g., see Patent Document 1). In the finish cutting step, when cut pieces of both the end portions removed from a main body of the honeycomb formed body are thin, there are possibilities that cutter blade edges escape to the outside to cause a perpendicularity defect and that the honeycomb formed body main body immediately after cut is damaged by the cutters. For the purpose of avoiding the above problems, it is necessary to set a cutting width of each end portion by the cutter to, e.g., at least 10 mm. On the other hand, an amount of the end face to be ground by the cup type grinding wheel (a grinding depth) is, for example, from about 1 to 2 mm. Consequently, there is formed the honeycomb formed body from which the deformation of the cells caused in the raw cutting step is removed, and the honeycomb formed body is sent to the subsequent firing step. For the large-size honeycomb structure, after the firing step, a circumferential surface of the honeycomb structure is ground and processed in a circumference grinding step to remove the deformation of the whole shape of the honeycomb formed body which is caused in the raw cutting step, and a circumferential wall is formed in a circumference coating step. On the other hand, in the case of a honeycomb structure for use as the car exhaust gas purifying catalyst carrier (hereinafter referred to as “the car exhaust honeycomb structure”, the above finish cutting step is only performed. Therefore, for the car exhaust honeycomb structure, in the finish cutting step, it is necessary to also remove the deformation of the whole shape of the honeycomb formed body which is caused in the raw cutting step.
[Patent Document 1] JP-A-2008-12786